The present invention relates generally to using a solvent to extract a solute from a sample and recovering the solvent, and more specifically to providing such extraction and recovery of the solvent in a less costly, more efficient, and more durable manner.
The extraction of solutes (solids or liquids) by solvents is used in various industries. Natural substances are conventionally extracted by liquid solvents at normal pressure, as, for example, in the extraction of oil from seeds. The solute is then separated from the solvent, and the solvent is recovered for use in extracting more solute.
However, there are generally problems of solvent residue in end products (solute). Additional processing steps then remove the solvent from the extracted solute. To solve this problem, previous publications discuss using supercritical carbon dioxide. However, supercritical gases require high pressures, thus requiring more energy.
A heat pump has been used to alleviate some of the costs associated with supercritical carbon dioxide systems. However, using supercritical gases require tightly controlled temperature and pressure values throughout the process, including in the extraction chamber, which can cause high design and operational costs. For example, a new system including the heat pump may need to be designed and tailored for every new application. Also, additional energy may need to be introduced into the extraction chamber, which may be a significant thermal mass and may be exposed to exterior fluctuations in ambient temperature, thus detracting the energy savings obtained by the heat pump.
Another problem identified by the present inventors is that a viscous solute may be deposited within machinery used before and during separation, which may occur when using liquid and supercritical solvents. For example, a vaporizer used just prior to a separator may experience fouling, resulting from the solute precipitating from the solvent. This can reduce operational performance, increase energy costs, and reduce the working lifetime of the machinery.
Therefore, it is desirable to have solvent extraction and recovery systems that can provide pure products without solute deposition problems, that do not require tightly controlled parameters throughout every part of the process, and that are cost and energy efficient.